Wireless communication technologies have been developed rapidly in recent years. Particularly a wireless ad hoc network has been applied in various fields due to its advantages of dispensing with any preset network facility, of rapid automatic networking, etc.
In the wireless ad hoc network, a mode in which a wireless channel is used is specified by the Medium Access Control (MAC) protocol, and a limited resource of wireless communication is allocated between nodes of the wireless network in the MAC protocol. Energy conservation and efficiency is targeted in a research of MAC layer protocols of the wireless ad hoc network due to the significance of network energy consumption to the wireless ad hoc network.
In order to lower the energy consumption of a network node, a period of time for communication of a network node is divided periodically into two portions, i.e., an active portion and an inactive portion, as illustrated in FIG. 1, in an MAC layer protocol of the wireless ad hoc network. The network node is in a working state during the active period of time and does not communicate with any other node in the network during the inactive period of time to thereby enter a sleeping state and consequentially conserve energy.
In the wireless ad hoc network, the same wireless channel is shared among a plurality of network nodes, and the respective nodes transmit random data or instructions. In order to alleviate a collision, a mechanism of accessing the shared channel is created in an MAC layer protocol. At present, a most common MAC layer protocol is the Carrier Sense Multiple Access/Collision Avoidance (CSMA/CA) protocol, and network nodes contest for the wireless channel resource during the active period of time in a mode of CSMA/CA to lower the probability of a collision. Therefore, during the active period of time, a node has to keep in working state all the time even if it has no data to be transmitted, so that it can sense the wireless channel for availability and receive at any moment an instruction transmitted thereto from another node, and both this constant sensing and frequent interaction of instructions may result in unnecessary energy consumption of the node.